Complex combinations of printing methods including intaglio printing, relief printing, and lithographic printing are used for printing securities and the like for the purpose of counterfeit prevention and so forth. Intaglio printing by which fine and sharp images can be obtained is used for portraits and denominations. Relief printing by which legible and sharp letters can be printed is used for serial numbers. Lithographic (offset) printing suitable for multi-color printing is used for background patterns. Further, a special printing method called collect-printing is employed for part of the background patterns.
The collect-printing is a printing method in which inks in different colors are attached respectively onto multiple pattern plate cylinders, and then the inks on the pattern plate cylinders are collected onto a collecting plate cylinder via a collecting blanket cylinder and are transferred further onto a sheet of paper passing between a blanket cylinder and an impression cylinder. This collect-printing has a great counterfeit prevention effect because the collect-printing has such a characteristic that no registration error occurs at all even when colors are changed in the middle of an image.
FIG. 8 shows a multi-color collect-printing press used for printing background patterns. In this printing press, three pattern plate cylinders (collect-printing pattern plate cylinders) 01, a collecting blanket cylinder (a collect-printing collecting blanket cylinder) 02, a collecting plate cylinder (a collect-printing collecting plate cylinder) 03, a blanket cylinder 04, and an impression cylinder 05 are connected in this order. Images on the respective pattern plate cylinders 01 are transferred to and integrated on the collecting plate cylinder 03 via the collecting blanket cylinder 02, and are further printed, via the blanket cylinder 04, on a sheet of paper that is fed from a not-illustrated sheet feeder to a space between the blanket cylinder 04 and the impression cylinder 05 via a swing 06. The printed sheet of paper is conveyed from a delivery cylinder 07 to a not-illustrated delivery device (see Patent Document 1).
While an offset printing press and a collect-printing press may be used in combination for printing background patterns, this configuration has a disadvantage of high installation costs because both of the printing presses have structures that are large in size. The configuration has another problem which is an increase in load on an operator when he or she conveys printed products on a palette from a delivery unit of the collect-printing press to a sheet feeder unit of the offset printing press with a forklift or the like while keeping the products away from collapsing.
The applicant of the present invention has previously proposed combination printing presses as described in Patent Documents 2 and 3, for example, which can perform both offset printing and collect-printing.